Element-wise addition of two list of different lengths?

Question

How to perform element-wise addition of different length lists?
Assuming \"0\" for missing elements.
Note: len(a) will always be less than or equal to len(b)

exa

Answer 1

You can use izip_longest:

>>> izip_longest(a,b,fillvalue=0)

>>> list(_)
[(1, 1), (2, 2), (3, 3), (0, 4), (0, 5)]

Then you can do:

>>> [sum(t) for t in izip_longest(a,b,fillvalue=0)]
[2, 4, 6, 4, 5]